death wobble!!!!!!!

Not to be rude but i'm just gonna post without a story lol,
bought the truck. has reverse triangulated 4 link, (which sucks) everything on this truck is brand new,
I have built around 5 mini trucks never had this problem, but never messed with a reverse 4 link either.
1-40 mph rides like a caddy, 40+ will beat the change out of your pockets, very very unsafe,
I got my dad to drive it, and he said it needs a panhard bar. all the tri links i built i never had to use one,
everything is true and tight, i checked everything over 20 times, wheels are good, links are same on both sides, the bottom two adjust top to dont, i honestly think the two bottom link bars are to high in the rear of the truck, the link tabs on the back of the truck, are all on the same plane, meaning if they where lined up right you could stick a piece of all thread through each hole at the same time, stright down the center of them all!!! bad deal isnt it? thats what i think, but someone else explain cause as of right now, reverse 4 links are as good as 4 pieces of rope, lol ,if need a pic i'll take it tomorrow, i'll show you what i have as of right now. also thanks for your time,
 
i'm truely stumped, ive ask a few other local mini truckers, and everyone is check drive shaft, check this check that, but i think its the height of the lower link bars at the back of the truck.
 
 

Your upper link mounting points should be higher, but either way your instant center is going to be wrong because its pointing at the back of your truck. What is your pinion angle at ride height? You could have a driveline vibration that you dont notice at low speeds if the pinion angle is bojangled.

Does the vibration occur at different heights?

Have you tried driving 40+ with the truck at maximum height and with the truck at minimum height?

sounds like the U joint... that reverse link is pulling on the driveshaft and more then likely pointing that thing up or down drastically cause it to bind and vibrate... I think your correct when you say that the bars are all mounted at the same height to the frame, which would really mess with the pinion angle, but more importantly it's the overall reverse link system thats actually causing the problem... 

So if I rea dit correctly, you said all the mounting points on the frame are at the same height, and you could put a rod through all of them if you wanted to? Thats the biggest issue right there, besides the fact that its reversed. You gotta be getting a ton of pinion angle change because what you have is an overly complicated reverse 2link! And since its probably been doing it since the setup was done, the u-joints are probably toast by now. Of course the fact that you have a 2-piece shaft isnt helping things either...

vibration?, I thought you said death wobble. From your description of the rear tabs i say, scary deathwobble, not a good feeling.  Your lower bars definitely need to be moved down, or the top ones moved up. Bad thing about moving the bottoms down is they are closer to hitting the ground.  I'd just flip the bars around to the front side and call it fixed.

Edited: 9/29/2009 9:56:48 PM by rangerfor22s

ive ran into this problem before on a rev. link on a s-dime,..it might be the lower axle tab bolt holes have worn egg shaped (and you cant see it until you take the bolt out) ,.just a guess but....if so, replace the lower axle tabs and put in  new bolts and ur good to go

i forget the pinion angle at ride height, i'll check tomorrow for you.. another question, since, i'm only front and back, whats the best link to use? if i'm gonna have to redo this, i'm gonna do it right, the 2nd time lol, screw some reverse links. a 2 link like a ladder bar setup with panhard bar would work fine right? and the 2 piece drive shaft was a mofo to get the pinion angle, saturday i'm gonna redo it and test drive in the same day if all goes well. alot of ppl would drive it like it is i'm sure, but its unsafe as a lighing tnt in your underware lol, so i'm just gonna redo it i think. i think the push pull difference on the rearend makes some difference too. even if it were perfect i still think it would be unsafe at 60mph, but i cant get that far yet lol,

my brothers s-10 with a reverse had a serious side to side swaying death wobble we tried all kind of stuff to fix it but nothing helped until we trashed the reverse and but a regular forward facing triangulated set up in it. From what I read up on a reverse setup it transfers momentum into the truck  instead of into the wheels and road. My brother couldn't do over 60 without worrying about losing control of the truck... it was even worse when you brake or go downhill becuase of the weight getting off the ass end it would really start to sway.. after we put the forward link in it we drove 250 miles to a show in NC 85-90 mph without any worries... you'll be much happieer to go ahead and ditch the reverse

i agree ditch the reverse and reuse your bars forward. u wll be much happier and so will your driveline. reverse setups jus do weird things